Responses:1)I’ve used both and I use Lean as the over arching strategy, culture, and problem solving lens. I use six sigma to dive deep into one process and control the variation of individual processes when needed.

2)I think six sigma is a tool, only one tool that can be applied in an appropriate moment during the lean transformation or problem solving.So for example you can apply DOE for seeing complex process problems or use different charts to visually display the state of the process. But lean thinking is more than just tools, it is a managerial philosophy, organisations management in all its parts, not only the relentless research for the best ROI in one process or for one specific problem.

3)I’ve been an MBB in GE and lived in the Lean world of Valeo. I have seen the merits of both, but there are clear differences as well.

The integration of the two is possible, but the way in which much depends upon the vision the company pursues.In the report I’ve sent you, you can also read back how companies integrate Lean and Six Sigma in different ways.For me the way you integrate both (if you desire to do so) is related to the essence of the two:– Six Sigma is a project approach and leads to improvement projects. You can chose to integrate Lean elements into this approach but it remains a project-oriented approach to improvement, mostly executed by specialists with specific job titles like change agent, black belt, etc.– Lean is not a project approach but does not contain elements that be used in such an approach. Most LSS approaches are project approaches with Lean elements. However, Lean in a broader sense is a system based upon principles in itself based upon a fundamental way of looking at the world. Can we integrate the project approach of Six Sigma and its tools into this system? Sure we can. But there is a big difference between Six Sigma with Lean and Lean with Six Sigma!

Put differently: is there a difference between continuously running improvement projects and continuous improvement?

If you have any thoughts or additions please post them in the comments section.